* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
    line-height: 1.7;
    color: #0f172a;
    background: #ffffff;
    padding-bottom: 60px;
}

/* ヘッダー */
.header {
    background: #0891b2;
    color: white;
    padding: 48px 20px 36px;
    text-align: center;
}

.header h1 {
    font-size: 22px;
    margin-bottom: 8px;
    font-weight: 600;
    letter-spacing: -0.02em;
}

.header-icon {
    font-size: 40px;
    margin-bottom: 12px;
}

/* パンくずリスト */
.breadcrumb {
    padding: 16px 20px;
    background: #f8fafc;
    border-bottom: 1px solid #e2e8f0;
}

.breadcrumb-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    list-style: none;
    font-size: 13px;
    color: #64748b;
}

.breadcrumb-item {
    display: flex;
    align-items: center;
    gap: 8px;
}

.breadcrumb-item::after {
    content: "›";
    color: #cbd5e1;
}

.breadcrumb-item:last-child::after {
    content: "";
}

.breadcrumb-link {
    color: #0891b2;
    text-decoration: none;
    transition: color 0.2s;
}

.breadcrumb-link:hover {
    color: #0e7490;
}

.breadcrumb-current {
    color: #334155;
}

/* メインコンテンツ */
.main-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 32px 20px;
}

.article-header {
    margin-bottom: 32px;
}

.article-title {
    font-size: 24px;
    font-weight: 700;
    line-height: 1.4;
    color: #0f172a;
    margin-bottom: 16px;
    letter-spacing: -0.02em;
}

.article-meta {
    display: flex;
    gap: 16px;
    font-size: 13px;
    color: #64748b;
}

/* 目次 */
.toc {
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 40px;
}

.toc-title {
    font-size: 16px;
    font-weight: 700;
    color: #0f172a;
    margin-bottom: 16px;
}

.toc-list {
    list-style: none;
}

.toc-item {
    margin-bottom: 8px;
}

.toc-link {
    color: #0891b2;
    text-decoration: none;
    font-size: 14px;
    transition: color 0.2s;
}

.toc-link:hover {
    color: #0e7490;
}

/* 記事本文 */
.article-body h2 {
    font-size: 20px;
    font-weight: 700;
    color: #ffffff;
    margin: 48px 0 24px;
    padding-bottom: 12px;
    border-bottom: 2px solid #e2e8f0;
    letter-spacing: -0.01em;
}

.article-body h3 {
    font-size: 18px;
    font-weight: 700;
    color: #0f172a;
    margin: 32px 0 16px;
    letter-spacing: -0.01em;
}

.article-body p {
    margin-bottom: 16px;
    line-height: 1.8;
    color: #334155;
}

.article-body ul,
.article-body ol {
    margin: 16px 0 16px 24px;
    color: #334155;
}

.article-body li {
    margin-bottom: 8px;
    line-height: 1.8;
}

.article-body ul ul,
.article-body ol ul {
    margin: 8px 0 8px 24px;
}

.article-body ul ul li,
.article-body ol ul li {
    margin-bottom: 6px;
    font-size: 14px;
}

.article-body strong {
    color: #0f172a;
    font-weight: 700;
}

/* テーブル */
.article-body table {
    width: 100%;
    border-collapse: collapse;
    margin: 24px 0;
    font-size: 14px;
    background: #ffffff;
    border: 1px solid #e2e8f0;
    border-radius: 8px;
    overflow: hidden;
}

.article-body th {
    background: #f8fafc;
    color: #0f172a;
    font-weight: 700;
    padding: 12px 16px;
    text-align: left;
    border-bottom: 2px solid #e2e8f0;
}

.article-body td {
    padding: 12px 16px;
    border-bottom: 1px solid #f1f5f9;
    color: #334155;
}

.article-body tr:last-child td {
    border-bottom: none;
}

/* ポイントボックス */
.point-box {
    background: #f0f9ff;
    border-left: 4px solid #0891b2;
    border-radius: 8px;
    padding: 20px;
    margin: 24px 0;
}

.point-box p:last-child {
    margin-bottom: 0;
}

/* 注意ボックス */
.note-box {
    background: #fef3c7;
    border-left: 4px solid #f59e0b;
    border-radius: 8px;
    padding: 20px;
    margin: 24px 0;
}

.note-box p:last-child {
    margin-bottom: 0;
}

/* 区切り線 */
.divider {
    height: 1px;
    background: #e2e8f0;
    margin: 40px 0;
}

/* FAQ セクション */
.faq-section {
    display: grid;
    grid-template-columns: 1fr;
    gap: 16px;
    margin: 32px 0;
}

.faq-item {
    background: #ffffff;
    border: 1px solid #e2e8f0;
    border-radius: 12px;
    overflow: hidden;
    transition: all 0.2s ease;
}

.faq-item:hover {
    border-color: #cbd5e1;
}

.faq-item:active {
    transform: scale(0.99);
}

.faq-question {
    padding: 20px 20px;
    cursor: pointer;
    display: flex;
    align-items: flex-start;
    gap: 14px;
    transition: all 0.2s ease;
}

.faq-icon {
    font-size: 20px;
    flex-shrink: 0;
}

.faq-text {
    flex: 1;
    font-size: 15px;
    font-weight: 600;
    color: #0f172a;
    letter-spacing: -0.01em;
    line-height: 1.5;
}

.faq-arrow {
    font-size: 14px;
    color: #64748b;
    transition: transform 0.3s ease;
    font-weight: 600;
    margin-top: 2px;
}

.faq-arrow.active {
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease, padding 0.3s ease;
    padding: 0 20px;
    background: #f8fafc;
}

.faq-answer.active {
    max-height: 800px;
    padding: 0 20px 24px 20px;
}

.faq-answer p {
    font-size: 14px;
    line-height: 1.8;
    color: #334155;
    margin-bottom: 12px;
}

.faq-answer p:last-of-type {
    margin-bottom: 0;
}

.faq-answer ul {
    margin: 12px 0 12px 20px;
}

.faq-answer li {
    margin-bottom: 8px;
    font-size: 14px;
    color: #334155;
}

.faq-answer ul ul {
    margin: 8px 0 8px 20px;
}

.faq-answer ul ul li {
    margin-bottom: 4px;
    font-size: 13px;
}

/* 関連記事 */
.related-articles {
    background: #f8fafc;
    border-radius: 12px;
    padding: 24px;
    margin-top: 48px;
}

.related-title {
    font-size: 18px;
    font-weight: 700;
    color: #0f172a;
    margin-bottom: 16px;
}

.related-list {
    list-style: none;
}

.related-item {
    margin-bottom: 12px;
}

.related-link {
    color: #0891b2;
    text-decoration: none;
    font-size: 15px;
    transition: color 0.2s;
}

.related-link:hover {
    color: #0e7490;
}

/* フッター */
.footer {
    background: #f8fafc;
    border-top: 1px solid #e2e8f0;
    padding: 32px 20px;
    margin-top: 60px;
    text-align: center;
}

.footer-nav {
    margin-bottom: 24px;
}

.footer-link {
    color: #0891b2;
    text-decoration: none;
    font-size: 14px;
    margin: 0 12px;
    transition: color 0.2s;
}

.footer-link:hover {
    color: #0e7490;
}

.copyright {
    font-size: 13px;
    color: #64748b;
}

/* 書籍カード */
.book-card {
    border: 2px solid #ff9966;
    border-radius: 12px;
    margin: 30px 0;
    background: #fff;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(255, 153, 102, 0.2);
    max-width: 100%;
    width: 100%;
}

.book-card-header {
    background: linear-gradient(135deg, #ff9966 0%, #ff8552 100%);
    color: #fff;
    padding: 12px 24px;
    font-weight: bold;
    font-size: 1.1em;
    display: flex;
    align-items: center;
    gap: 10px;
}

.book-card-header-icon {
    font-size: 1.3em;
    line-height: 1;
}

.book-card-body {
    padding: 24px;
}

.book-link {
    display: flex;
    flex-direction: row;
    gap: 20px;
    text-decoration: none;
    color: inherit;
    align-items: flex-start;
}

.book-link:hover {
    text-decoration: none;
}

.book-image-container {
    flex-shrink: 0;
    width: 160px;
    min-width: 160px;
    max-width: 160px;
    margin: 0;
    padding: 0;
}

.book-image {
    width: 100%;
    height: auto;
    display: block;
    border-radius: 6px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    margin: 0;
    padding: 0;
}

.book-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 0;
}

.book-title {
    font-size: 1.3em;
    margin: 0 0 12px 0;
    padding: 0;
    color: #2c3e50;
    line-height: 1.5;
    font-weight: bold;
    border: none;
    background: none;
}

.book-description {
    color: #666;
    line-height: 1.7;
    margin: 0 0 16px 0;
    padding: 0;
    font-size: 0.95em;
    flex-grow: 1;
}

.book-button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    background: #ff9966;
    color: #fff;
    padding: 12px 28px;
    border-radius: 25px;
    font-weight: bold;
    font-size: 0.95em;
    align-self: flex-start;
    text-decoration: none;
    border: none;
    cursor: pointer;
    width: fit-content;
    transition: background 0.2s;
}

.book-button:hover {
    background: #ff8552;
}

/* レスポンシブ */
@media (max-width: 768px) {
    .article-title {
        font-size: 20px;
    }

    .article-body h2 {
        font-size: 18px;
        margin: 40px 0 20px;
    }

    .article-body h3 {
        font-size: 16px;
        margin: 28px 0 14px;
    }

    .article-body table {
        font-size: 13px;
    }

    .article-body th,
    .article-body td {
        padding: 10px 12px;
    }

    .book-link {
        flex-direction: column;
        gap: 16px;
    }

    .book-image-container {
        width: 100%;
        max-width: 200px;
        margin: 0 auto;
    }
}